This invention relates to a scroll compressor provided with an orbiting scroll and a fixed scroll for use as a compressor of a refrigerator, an air conditioner, etc.
FIG. 16 is a longitudinal sectional view of a conventional scroll compressor, for example, disclosed in Japanese Patent Laid-Open No.Sho 62-265487, wherein numeral 1 is a sealed vessel and numeral 2 is a fixed scroll provided with a base plate 4 fixed to an upper frame 3 having an outer peripheral surface secured to one end face in the sealed vessel 1, a discharge port 5 disposed at the center of the base plate 4, and a plate-like spiral tooth 6 disposed on the side of the upper frame 3 of the base plate 4.
Numeral 7 is a partition plate secured in the sealed vessel 1, placed on the side of the base plate 2 of the fixed scroll 2 opposed to the upper frame 3, and provided with a discharge port 8 at the center. Numeral 9 is a discharge valve having a valve guard mounted on the side of the partition plate 7 opposed to the fixed scroll 2 with a bolt 11. Numeral 12 is an orbiting scroll disposed between the fixed scroll 2 and the upper frame 3 and having a base plate 13 provided with a plate-like spiral tooth 15 engaging the plate-like spiral tooth 6 of the fixed scroll 2 for forming a compression space 14.
Numeral 16 is an orbiting shaft disposed on the side of the base plate 13 of the orbiting scroll 12 opposed to the fixed scroll 2. Numeral 17 is a thrust face which is formed on the side of the orbiting shaft 16 of the base plate 13 of the orbiting scroll 12 and comes in plane contact with a thrust bearing 18 of the upper frame 3 for sliding. Numeral 19 is an Oldham's ring having an upper claw engaged slidably in a linear direction in a pair of Oldham's guide grooves formed on the outer peripheral surface of the base plate 13 of the orbiting scroll 12.
The upper frame 3 is also formed with Oldham's guide grooves having a phase difference of about 90.degree. with the Oldham's guide grooves of the orbiting scroll 12, in which a lower claw of the oldham's ring 19 is engaged slidably in a linear direction.
Numeral 20 is a lower frame which has an outer peripheral surface secured in the sealed vessel 1, is placed on the side of the upper frame 3 opposed to the orbiting scroll 12, and is provided with a main bearing radially supporting a main shaft 22 driven by an electric motor 21 at the center.
Numeral 24 is an orbiting bearing which is disposed at an end of the orbiting scroll 12 side of the main shaft 22 and is formed like a circular cylinder eccentric in the same direction as the eccentric direction of the orbiting scroll 12 for pivotally supporting the orbiting shaft 16 of the base plate 13 of the orbiting scroll 12.
Numeral 25 is a suction pipe for guiding a low-pressure refrigerant gas before compressed to the inside of the sealed vessel 1 and numeral 26 is a discharge pipe for discharging a high-pressure refrigerant gas after compressed to the outside of the sealed vessel 1.
Numeral 27 is a high pressure space formed between the end face of the sealed vessel 1 and the partition plate 7. Numerals 28 to 30 are a compression space 14 formed like a pair of crescents with the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate-like spiral tooth 15 of the orbiting scroll 12; numeral 28 is a high pressure chamber, numeral 29 is an intermediate pressure chamber, and a numeral 30 is a low pressure chamber. Numeral 31 is a compression high pressure section formed by the high pressure chamber 28, the discharge port 5 of the fixed scroll 2, and the discharge port 8 of the partition plate 7.
The conventional scroll compressor has the above structure. When the electric motor 21 is energized, the orbiting scroll 12 is driven via the main shaft 22 and the orbiting shaft 16. At this time, rotation of the orbiting scroll 12 with respect to the upper frame 3, namely, the fixed scroll 2 is restrained by the Oldham's ring 19. Thus, the orbiting scroll 12 makes the orbiting motion with respect to the fixed scroll 2.
A refrigerant gas sucked through the suction pipe 25 is taken in the low pressure chamber 30 of the compression space 14 formed like a pair of crescents with the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate-like spiral tooth 15 of the orbiting scroll 12.
The compression space 14 decreases in volume in order from the low pressure chamber 30 to the intermediate pressure chamber 29 to the high pressure chamber 28, whereby the refrigerant gas is compressed.
Next, the compressed high-pressure refrigerant gas passes through the discharge port 5 of the fixed scroll 2 and the discharge port 8 of the partition plate 7, pushes and opens the discharge valve 9, is discharged into the high pressure space 27, and is sent outside the sealed vessel 1. Just after the scroll compressor stops, the discharge valve 9 is closed, preventing the refrigerant gas in the high pressure space 27 from passing through the compression high pressure section 31 and flowing reversely to the refrigerant gas flow at the normal motion time, thereby blocking the reverse orbiting operation of the orbiting scroll 12 to the normal motion time.
The discharge valve 9 opens for discharging high-pressure refrigerant gas almost throughout the time from starting to stopping of the scroll compressor operation. The operating scroll compressor has a characteristic wherein the high pressure chamber 28 and the intermediate pressure chamber 29 formed by the plate-like spiral tooth 6 of the fixed scroll 2 and the plate-like spiral tooth 15 of the orbiting scroll 12 are communicated with each other at a predetermined timing.
Just after the high pressure chamber 28 and the intermediate pressure chamber 29 are communicated with each other, the pressure in the compression high pressure section 31 becomes lower than the pressure in the high pressure space 27, closing the discharge valve 9. An impulse wave is produced in the compression high pressure section 31 by water hammering of the refrigerant gas in the vicinity of the discharge valve 9 when the discharge valve 9 is closed. A pressure ripple in the discharge port 5 of the fixed scroll 2 caused by the impulse wave becomes a vibration source, increasing noise of the scroll compressor.
FIGS. 17, 18A, and 18B show another conventional scroll compressor, for example, disclosed in Japanese Patent Laid-Open No.Sho 62-75089. FIG. 17 is a longitudinal sectional view of the main part of the conventional scroll compressor and each of FIGS. 18A and 18B is a plan view explaining the operation of the scroll compressor in FIG. 17. Parts not shown in FIG. 17, 18A or 18B are the same as those of the scroll compressor in FIG. 16. Parts identical with or similar to those previously described with reference to FIG. 16 are denoted by the same reference numerals in FIGS. 17, 18A and 18B. Numeral 32 is an orbiting bearing disposed on the side of a base plate 13 of an orbiting scroll 12 opposed to a fixed scroll 2, in which an orbiting shaft 16 of the base plate 13 of the orbiting scroll 12 is fitted rotatably.
Numeral 33 is a thrust member which is disposed on a surface facing the base plate 13 of the orbiting scroll 12 of an upper frame 3 and comes in plane contact with the base plate 13 for sliding. Numeral 34 is an Oldham's guide groove formed in the upper frame 3 and placed forming a phase difference of about 90.degree. with an Oldham's guide groove of the orbiting scroll 12, in which a lower claw 35 of an Oldham's ring 19 is engaged slidably in a linear direction.
Numeral 36 is a counterboring part disposed in a base plate 4 of the fixed scroll 2 and having a cutaway part corresponding to the center of a plate-like spiral tooth 6. Numeral 37 is a counterboring part disposed in the base plate 13 of the orbiting scroll 12 and having a cutaway part corresponding to the center of a plate-like spiral tooth 15.
The conventional scroll compressor has the structure. When an electric motor 21 is energized, the orbiting scroll 12 is driven via a main shaft 22 and the orbiting shaft 16. At this time, rotation of the orbiting scroll 12 with respect to the upper frame 3, namely, the fixed scroll 2 is restrained by the Oldham's ring 19. Thus, the orbiting scroll 12 make the orbiting motion with respect to the fixed scroll 2.
A refrigerant gas sucked through a suction pipe 25 in taken in a low pressure chamber 30 of a compression space 14 formed like a pair of crescents with the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate-like spiral tooth 15 of the orbiting scroll 12.
The compression space 14 decreases in volume in order from the low pressure chamber 30 to an intermediate pressure chamber 29 to a high pressure chamber 28, whereby the refrigerant gas is compressed.
Next, the compressed high-pressure refrigerant gas is discharged through the counterboring part 36 of the fixed scroll 2, the counterboring part 37 of the orbiting scroll 12, and a discharge port 5 of the fixed scroll 2. As shown in FIG. 18, the counterboring part 36 of the fixed scroll 2 and the counterboring part 37 of the orbiting scroll 12 defining a flow passage of high-pressure refrigerant gas at a predetermined timing are communicated with the intermediate pressure chamber 29.
Therefore, the counterboring part 36 of the fixed scroll 2 and the counterboring part 37 of the orbiting scroll 12 provide a discharge flow passage when the refrigerant gas is discharged, decreasing a discharge pressure loss, thereby decreasing scroll compressor input caused by the discharge pressure loss. However, when the counterboring parts 36 and 37 are communicated with the intermediate pressure chamber 29, the high-pressure refrigerant gas is returned to the intermediate pressure chamber 29, then again discharged through the discharge port 5 of the fixed scroll 2 by the compression operation of the compression space 14.
In the conventional scroll compressor as described above, if the discharge valve 9 is omitted, the orbiting scroll 12 performs the reverse orbiting operation to the normal motion time just after the scroll compressor stops. Since it is feared at the time that reverse rotation noise may be produced or that the orbiting bearing 32, etc., may be damaged depending on the situation, the discharged valve 9 is provided.
However, if the discharged valve 9 is closed during the operation of the scroll compressor, an impulse wave is produced in the discharge port 5 of the fixed scroll 2 by water hammering of the refrigerant gas in the vicinity of the discharge valve 9. Noise occurs with the impulse wave as a vibration source, causing noise of the scroll compressor to increase.
The counterboring part 36 of the fixed scroll 2 and the counterboring part 37 of the orbiting scroll 12 defining a flow passage of high-pressure refrigerant gas at a predetermined timing during the operation of the scroll compressor are communicated with the intermediate pressure chamber 29. Since the pressure in the intermediate pressure chamber 29 of the compression space 14 instantly increases just after they are communicated, the fixed scroll 2 and the orbiting scroll 9 are vibrated, increasing noise of the scroll compressor.